1. Field of the Invention
The present invention relates to a bone evaluation method. More specifically, it relates to a bone evaluation method in which a bone pattern is determined by measuring the photodensity of X-ray photographs of the long bone of a limb or by photon absorptiometry from the long bone of a limb, the resultant bone pattern is modified, and the bone is evaluated based on the resultant modified bone pattern.
2. Description of the Related Art
The so-called microdensitometry (MD) method has heretofore been known as a method for evaluating bone, for example, growth conditions of human bone, aging degree of human bone, or kinds of bone diseases such as osteoporosis and osteomalacia, as disclosed in, for example, "Kotsu Taisha" (i.e., Bone Metabolism) 13, pp 187-195 (1980) and 14, pp 91-104, (1981). According to the MD method, the photodensity of X-ray photographs is measured at the middle site of a metacarpal bone with a microdensitometer and various indices such as an index of the bone cortical width (MCI), a bone width (D), a maximum bone density (GSmax), a minimum bone density (GSmin), a bone mineral content (.SIGMA.GS), and an average bone density (.SIGMA.GS/D) are determined. The degree of osteanabrosis is thus evaluated based on the above-determined indices.
Another known method for evaluating bone is so-called photon absorptiometry. According to this method, a .gamma.-ray is used instead of an X-ray and the amount of the .gamma.-ray transmitted through bone is measured by a detector, followed by a quantitative treatment.
However, in the MD method, various indices such as the maximum bone density (GSmax) and the bone cortical width (MCI) sometimes do not reflect the actual bone conditions and, therefore, the desired evaluation of bone based on these indices becomes difficult. For example, although it is believed that the maximum bone density (GSmax) is an index representing the bone density of a bone cortex, the GSmax values will vary in accordance with the diameter of the bone and the bone cortex width even where the bones have the same bone density. Furthermore, when the bone is not homogeneous, exactly what the GSmax values represent becomes unclear.
On the other hand, the conventional photon absorptiometry method is only used for the determination of bone mineral content (BMC).